For a long time I’ve been using a Drobo connected to my Airport Extreme base station as a backup drive for Time Machine. I know it’s not a supported configuration, but it’s a lot more practical than having to keep an external drive plugged in to my MacBook Pro, which I often move around so I can work in different rooms. There is no good reason it shouldn’t work the same way a Time Capsule does. I don’t like the Time Capsule because it uses a single drive and can’t be expanded like the Drobo.
It works most of the time, but after a while it gets very slow and once in a while it corrupts my backup sparse image. After using it for several months, a single backup often takes longer than a day and if I put my MacBook Pro to sleep when it’s preparing or finishing a backup, that backup fails. The last few times it took over a week to successfully complete a single backup.
After my backup image got completely trashed and couldn’t be repaired, I decided to look for other backup options. CrashPlan is the best backup solution I’ve found for several reasons. Like Time Machine, CrashPlan runs continuously in the background. CrashPlan maintains multiple versions of files and can restore a particular version.
Unlike many other backup programs such as Mozy which are tied to a particular online service, CrashPlan gives you several options for backing up. In addition to CrashPlan’s own CrashPlan Central online backup service, you can back up to any folder (including a mounted server volume such as my Drobo) or another computer running CrashPlan. You can also invite friends to back up to your computer or back up to a friend’s computer. You can even back up to multiple destinations at the same time.
After trying it for a few days, I upgraded to CrashPlan+, which backs up continuously instead of once a day. I’m still on my 30-day free trial of CrashPlan Central, but I will probably opt for their $100/year family plan, which will let me back up multiple computers.